Screwstrips are known wherein the screws are connected together by a retaining strap, preferably of plastic material, and adapted to be fed into an autofeed screw fastening tool and successively driven from the belt as the screwstrip is advanced through the tool. Known screwstrips of this type include those referred to and disclosed in U.S. Pat. No. 4,167,229 to Keusch et al, issued Sep. 11, 1979 and Canadian Patent 1,054,982 to Schwarz, issued May 22, 1979 and the present applicant's U.S. Pat. No. 5,758,768, issued Jun. 2, 1998, U.S. Pat. No. 5,927,163, issued Jul. 27, 1999, and U.S. Pat. No. 6,494,322, issued Dec. 17, 2002, the disclosures of which are incorporated herein by reference. Such screwstrips are adapted to be driven in autofeed screwdrivers, such as taught by the applicant's U.S. Pat. No. 5,568,753, issued Oct. 29, 1996, U.S. Pat. No. 5,934,162, issued Aug. 10, 1999 and U.S. Pat. No. 5,870,933, issued Feb. 16, 1999, the disclosures of which are incorporated herein by reference.
The present inventor has pioneered the use of such screwstrips of shorter discrete length, for example, 12 inches (30 cm), as taught by the aforementioned U.S. Pat. No. 5,758,768 and U.S. Pat. No. 6,494,322, and particularly the use of “curved” such screw strips as particularly described with reference to the embodiment illustrated in FIG. 15 of U.S. Pat. No. 6,494,322.
Previously known methods for manufacturing screwstrips are disclosed in above-noted U.S. Pat. No. 4,167,229, U.S. Pat. No. 3,992,852 to Schwarz et al, issued Nov. 23, 1976 and U.S. Pat. No. 5,609,712 to Takumi, issued Mar. 11, 1997.
These patents generally teach holding screws in a straight line as on a moving chain or between two moving chains and extruding plastic material to form the holding strap from one or more stationary extrusion dies on to the moving screws typically with the screws and extrudate to be passed between forming rollers. These patents do not provide for manufacture of curved screwstrips.